The invention generally deals with systems and methods for loading and unloading multiple samples to be tested in a high voltage environment using a two piece test fixture.
Today, electronic devices are stringently tested in a production cycle; two of these tests are electrical surge and Accelerated Dielectric Testing (ADS). Typically devices will not be operated under the extreme conditions present in the surge and ADS tests, but devices may experience these conditions on occasion. Such occasions include lightning strikes, downed power lines, or the operation of high power equipment and utilities.
When an electronic device is exposed to extreme conditions, it is important that the device operates normally afterwards. The surge and ADS tests recreate extreme conditions that electronic devices may be exposed to during their lifetime. After completion of the tests, it is determined whether a tested sample suffered a breakdown and no longer operates as intended.
ADS testing is the application of a high voltage AC stress to accelerate the wear out of the isolation barrier and package. For example, one testing standard for ADS requires 5.7 kV to be applied for 64 hours. Surge testing is the application of 50 high voltage pulses designed to break the isolation barrier of a sample.
Surge and ADS both require a large voltage for testing, which presents additional difficulties. In many electrostatic discharge (ESD) environments, various measures are taken to reduce electrostatic discharges that may damage the samples under testing at low voltages.
Many ESD environments implement measures to reduce electro-static discharges such as a grounded floor, grounded wrist straps, and discharge mats to allow any electrostatic build up to be dissipated safely.
The problem with surge and ADS testing is that the large voltages required will be discharged to ground through a person handling the samples, via the ES safety measures, leading to shock or electrocution. For this reason, standard ESD safety measures are not an option when performing ADS and surge testing. The lack of safety measures protects the operator, but leaves the samples under testing susceptible to smaller electrostatic discharges that may occur during the handling and transportation of the samples.
FIG. 1 illustrates a conventional surge test system 100.
As illustrated in the figure, system 100 includes a chip mounting area 102, and a chip 104.
Chip mounting area 102 is arranged such that when chip 104 is mounted, the input of chip 104 is connected to input line 106 and the output of chip 104 is connected to output line 108.
Chip 104 is operable to receive an input, via input line 106, and convert it into an output. Chip 104 is additionally operable to transmit the output, via output line 108.
In operation, an operator will be instructed to perform a high voltage surge test on chip 104. At this point the operator will mount chip 104 in chip mounting area 102. Chip mounting area 102 is located in a high voltage area where ESD safety measures such as grounded flooring, grounded wrist straps, and discharge mats cannot be used. Due to the lack of these safety measures, there is the possibility that chip 104 may be damaged by an electrostatic discharge.
After chip 104 is mounted, the operator begins the high voltage surge test. During the test, a plurality of high voltage signals are input to chip 104, via input line 106. The high voltage signals pass through chip 104 and are then transmitted to ground, via output line 108. Each output signal can then be analyzed to detect a breakdown in the isolation barrier of chip 104.
Performing surge testing in this manner requires that one chip be tested at a time. Surge testing requires the output signal to be analyzed, so testing multiple chips in parallel is not performed since the output of multiple samples would be superimposed into a single signal. The superposition of multiple signals into a single output signal prevents an operator from being able to identify the specific device sample that failed.
A problem with the current system and method for performing surge testing is that testing multiple chips prevents failure identification. The inability to test multiple samples is problematic in a production environment which requires a large number of samples to be tested fir quality control purposes.
Another problem with the current system and method for performing surge and ADS testing is that standard safety measures used to protect people and testing samples in a low voltage ESD environment are quite dangerous in a high voltage ESD environment.
Accordingly, for at least the foregoing reasons there exists a need for performing surge testing of multiple samples while simultaneously discharging electrostatic build up safely.